When you think about World War II tech, chances are your mind leaps right to the atomic bomb. But there was another less explosive tech that complete changed the defensive game: Radar. And this map outlines exactly how it saved Great Britain.

As this map shows, Great Britain's radar "force field" extended all along its coast, pulsing out from high and low-level radar stations. These electronic ears-which could "hear" all the way into Nazi-occupied Belgium and France—gave the Brits the edge they needed to catch wave of Nazi bombers early, with time to intercept them with slower, but more agile fighters.

It really helps put into the perspective the invisible barrier that helped defend Great Britain against an almost impossible onslaught. Guns and planes helped too, but radar ain't nothing to sneeze at. [Maps on the Web]